Adjustable deflection yoke mounting for color picture cathode ray tubes



M. J. OBERT ETAL ADJUSTABLE DEFLECTION YOKE MOUNTING FOR Jan. 31, 196? 3,302,050

COLOR PICTURE CATHODE RAY TUBES 5 Sheets-Sheet 1 Filed July 15, 1964 I) R vm m WWW a W W0 17 m a M i MM, 5 M M4 4 61 k 0 m z/ J MU/ .7

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ADJUSTABLE DEFLECTION YOKE MOUNTING FOR COLOR PICTURE CATHODE RAY TUBES Filed July 15, 1964 5 Sheets-Sheet z Ilia/a Jan. 31, 1967 M QBERT ETAL ADJUSTABLE DEFLECTION YOKE MOUNTING FOR COLOR PICTURE CATHODE RAY TUBES 5 Sheets-Sheet 5 Filed July 15, 1.964

I VENTORJ Mmwmm/J fiiiPT Jaw/V M fl/w/MM/M ADJUSTABLE DEFLECTION YOKE MOUNTING FOR COLOR PICTURE CATHODE RAY TUBES Maximilian J. Obert and John M. Ammerman, Indianapolis, Ind., assignors to Radio Corporation of America, a

corporation of Delaware Filed July 15, 1964, Ser. No. 382,786 9 Claims. (Cl. 313-77) This invention relates to an adjustable deflection yoke mounting for a multiple electron beam color picture tube.

In color television receivers a popular type of image reproducing device is a cathode ray tube having three electron beams to selectively excite groups of phosphors capable respectively of producing light of three different colors such as red, green and blue. Such a tube has a luminescent screen made up of a plurality of triads of phosphor dots which are excited by respective electron beams projected through suitable placed apertures in a shadow mask located in back of the screen. The beams strike their respective phosphor dots by approaching them through the shadow mask from different directions.

The electron guns producing the three beams are located in a neck portion of the cathode ray tube and are spaced symmetrically about the longitudinal axis of the tube so that the beams can be made to intersect or converge at the shadow mask. The beams are deflected to scan respective rasters at the screen by means of a single deflection yoke. One commonly employed arrangement of the electron guns, and hence the electron beams emanating respectively therefrom, is with the blue gun located directly above the longitudinal tube axis and with the red and green guns located below this axis and respectively at oppoiste sides of the axis horizontally. The electron beams therefore necessarily traverse different sections of the deflection yoke field which is so designed to cooperate with other apparatus as to effect optimum beam register on the respective color phosphor dots, simultaneously with deflection and convergence of the three beams over the entire picture reproducing area scanned at the luminescent screen.

The other apparatus used in cooperation with the deflection yoke includes magnetic structures so designed and controlled as to move all of the beams radially with respect to the longitudinal axis of the cathode ray tube. Such radial movement of the beams is effected both statically and dynamically. By means of static convergence apparatus including means to move the three beams radially and means to effect a lateral (i.e. horizontal) movement of the blue beam relative to the red and green beams, the three beams may be converged at the center of the viewing screen. The dynamic convergence apparatus is energized suitably at both the horizontal and vertical deflection rates to move all of the beams radially with respect to the longitudinal tube axis to suitable degrees as a function of the beam deflection angle to effect convergence of beams and registration on the phosp'hor dots throughout the entire picture reproducing area scanned at the screen. By reason of the locations of the beams relative to the longitudinal tube axis it is possible by means of the dynamic convergence apparatus to impart radial motion (which includes both vertical and horizontal components) to the red and green beams. It is possible, however, to impart only a vertical movement of the blue beam by means of such dynamic convergence apparatus.

As previously indicated, the initial convergence of the three electron beams at the center of the screen is achieved by statically controlled magnetic apparatus. Such control may be effected by either permanent or electromagnets. In color television receivers in which cathode ray tubes having beam deflection angles not substantially United States Patent 3,392,050 Patented Jan. 31, 1967 in excess of 70, it has been possible by means of static and dynamic convergence apparatus, such as that described, to obtain good overall convergence of all three beams (i.e. registration of all three rasters). Because of the described beam arrangement relative to the longitudinnal axis of the picture tube and the particular character of the deflection yoke flux field needed to meet other necessary requirements, there is a tendency for one raster (e.g. the blue one) to be of a different width (eg. greater) than the other two when full screen static and dynamic convergence is achieved. In the past, the yoke and convergence apparatus has been capable of producing satisfactory convergence of all three electron beams throughout the entire picture area. In other words, satisfactory registration of the red, green and blue rasters has been achieved.

With the advent of greater beam deflection angles (e.g. it has not heretofore been possible easily to achieve satisfactory beam convergence at the sides of the picture area. Although the deflection yoke might be redesigned to correct such beam misconvergence or nonregistration of the three rasters, it likely would be at the cost of introducing other convergence errors which would appear in other areas of the picture. This, of course, would be more objectionable than any error appearing in the side areas of the picture. Additionally, any production variations in the deflection yoke probably would result in dilferences in the relative widths of the three rasters.

As one possible solution of the problem it has been suggested to provide a dynamic lateral adjustment of one beam which, in the described arrangement, would be the blue beam. Such a solution, however, requires additional apparatus and circuit means for its energization. This adds another complication to the receiver and also increases its cost of manufacture and operation.

Therefore, it is an object of the present invention to provide a simple, inexpensive means for effecting convergence of a plurality of electron beams throughout the entire picture area scanned at a luminescent screen by the respective beams.

In accordance with an embodiment of the present invention, there is provided an adjustable mounting for the deflection yoke. The yoke mounting enables precise adjustment of the deflection yoke both circutntferentially around the longitudinal tube axis and also longitudinally of this axis. Additionally, facilities are included to change the elevation of at least the rear end of the yoke relative to the three electron beams and as a result eifeot substantially complete registration of all three rasters.

An illustrative body of the invention is more fully disclosed by the following description which is taken in conjunction with the accompanying drawings of which:

FIGURE 1 is a profile diagrammatic View of a threebeam color cathode ray tube which is partially broken away to show some of the pertinent internal elements and also illustrating the general arrangement of the essential external adjuncts employed in the operation of such a tube;

FIGURE 2 is a cross sectional view taken in the line 22 of FIGURE 1 and showing the relative locations of the three electron beams and also the general arrangement of some of the beam convergence apparatus;

FIGURE 3 is a side view of the deflection yoke mounting structure which is partially broken away and crosssectioned to show the essential details of the structure and also the arangement of a form of the yoke elevating means embodying the invention;

FIGURE 4 is a perspective view of the yoke elevating means;

FIGURE 5 is 'a sectional view of the yoke mounting structure taken on the line 55 of FIGURE 3 and showing further details of the mounting structure including the elevating means for the deflection yoke;

FIGURE 6 is a diagrammatic representation of the unconverged rasters scanned at the screen of the cathode ray tube by deflecting the three electron beams;

FIGURE 7 is a diagrammatic representation of the scanned rasters produced by deflecting the three electron beams which have been converged both statically and dynamically as they would appear in the absence of the use of the present invention; and

FIGURE 8 is a diagrammatic representation of the three rasters produced by deflecting the three electron beams which have been statically and dynamically converged and employing the yoke elevating embodiment of the invention.

Reference first is made to FIGURE 1. The threebeam shadow mask type of color picture tube 10 has a relatively large flared front section 11 and a relatively small cylindrical rear neck section 12. The face plate 13 at the front of the flared section 11 has formed on its rear surface a fluorescent screen 14- comprising a plurality of triads of phosphor dots which are excitable by respective electron beams to produce light of three different colors such as red, green and blue. A shadow mask 15 having a plurality of apertures aligned with the triads of phosphor dots of screen 14 is mounted in back of the screen and functions in cooperation with other elements of the tube to direct the three electron beams to their respective phosphor dots. Three electron guns, of which only the blue gun 16 and the red gun 17 are visible, are mounted in the neck section 12 of the picture tube 10 to produce, when suitably energized, the three electron beams for excitation of the screen 14. The green electron gun is mounted directly on the same horizontal line with the red electron gun 17 so that it is not visible in this figure.

A deflection yoke 18 is mounted externally of the tube 10 in the region in which the neck section 12 merges with the flared sections 11. It is the particular mounting structure for such a yoke with which the present invention is concerned and which will be described subsequently. A beam convergence apparatus 19 is indicated diagrammatically as located surrounding the neck section 12 immediately to the rear of the deflection yoke 18. Still further to the rear on the neck section 12 there are located a color purity device 20' and a lateral magnet 21 behind it. The color picture tube 10 and the various adjuncts referred to are known and commonly used and hence need no further description or explanation.

In order to better understand the problem which the present invention solves, it is necessary to take into account some of the geometrical factors arising from the particular placement of the electron guns and the paths traversed by the electrons emanating therefrom. For this purpose, brief reference now is made also to FIGURE 2 which is a view looking toward the rear of the picture tube from the viewing screen thereof. The three electron guns such as the blue and red guns 16 and 17 of FIGURE 1 are mounted symmetrically about the longitudinal axis 22 of the tube. The blue electron beam B is located directly above the longitudinal axis. The red and green electron beams R and G, respectively, are located below the axis 22 and at opposite sides thereof in a horizontal sense. The convergence apparatus which is included in the means for effectively converging these three beams at all points in the respective rasters scanned thereby at the viewing screen includes pole pieces associated with each of the electron beams. For example, the pole pieces 23 associated with the blue beam B when suitably energized by an exciting magnet 24 located externally of the tube neck 12 are effective to move the blue beam radially relative to the axis 22. Similar apparatus is provided for each of the red and green beams R and G, respectively. Such structure is known and commonly used for achieving the desired convergence of the three electron beams at the screen 14 of the picture tube.

It is to be noted that, in the radial movement of the red and green beams relative to the axis 22, there are imparted both vertical and horizontal components to these beams. The blue beam, however, may be subjected only to a vertical component of movement. It, therefore, has been necessary to provide for the horizontal or lateral movement of the blue beam relative to the red and green beams in order to achieve the desired beam convergence. In the apparatus which has been previously used with a color cathode ray tube in which the beams are subjected to a relatively small angle of defleotion (elg. it has been necessary to provide this additional lateral movement of the blue beam relative to the red and green beams only on a static basis. That is, the initial convergence statically of the three beams at the center of the picture area has been achieved by permanent magnets operating as part of the convergence magnet structure 24- and the additional permanent magnet apparatus referred to previously as the lateral magnet 21. It has been found, however, that with greater angles of deflection, such as or more for example, it has not been possible to achieve satisfactory convergence of all three beams in the extreme left and right areas of the picture screen.

Satisfactory convergence of the red and green rasters has been possible by suitably energizing the convergence magnet structure dynamically with waveforms of suitable shape. Such achievement has been enabled by the fact that it has been possible to impart lateral or horizontal components of movement to the red and green electron beams by means of the internal pole piece apparatus exemplified by the pole pieces 23. Because of the geometrical arrangement of the picture tube apparatus, however, no such lateral movement is possible for the blue beam as previously indicated. Consequently, one means by which the necessary lateral movement of the blue electron beam has been achieved dynamically is by providing additional controlling apparatus for this beam together with energizing circuitry therefor. The apparatus embodying the present invention which is now to be described obviates the need for such additional dynamic blue beam lateral deflection apparatus.

For a description of such apparatus reference now is made to FIGURES 3, 4 and 5 of the drawings. The deflection yoke mounting illustrated consists generally of three major elements. One of these elements is a hollow, generally cylindrical housing 25. This housing has an annular front end 26 including a plurality of forwardly extending projections 27. These projections are pressed into engagement with the rear portion of the flared front section 11 of the color picture tube 10.

The second major element of the yoke mounting consists of an annular frame 28 which is interlocked with the rear end 29 of the housing 25. This frame serves as a mounting means for the convergence coils, such as the blue coil 24. It encircles the neck section 12 of the color picture tube and is securely attached to the neck section by means of a plurality of rearwardly extending fingers 31 which are brought into firm engagement with the neck section 12 by means such as an encircling clamp 32.

The housing 25 is provided with a number of slots, some of which are formed adjacent to the front end and some adjacent to the rear end of the housing. In the front portion of the housing 25 a lower slot. 34 is provided and a plurality of lateral slots such as the slot 35. A slot 35a similar to the slot 35 may be formed in the housing on the opposite side of the picture tube. In the rear portion of the housing 25 a lower slot 36 and two lateral slots 37 and 38 are provided. All of these slots are for the purpose of receiving keys formed in one of the other main elements of the mounting which will now be described.

This third element of the yoke mounting comprises a half-shell upwardly opening support 39 for the deflection yoke. The half-shell support includes front and rear approximately semi-circular rims 41 and 42. In the embodiment shown, the front rim 41 has a radius of curvature which is larger than that of the rear rim 42. The half-shell support also has a generally frustoconical section 43 joining the front and rear rims 41 and 42. The half-shell support 39 also has a plurality of outwardly extending keys formed respectively in the front and rear rims 41 and 42. The front rim 41 has a lower key 44 adapted to slide longitudinally of the picture tube in the lower front slot 34 of the housing 25. The halfshell support also has two lateral front keys 45 and 45a which are adapted to slide in the lateral front slots 35 and 35a respectively of the housing 25. The support 39 has two lateral keys 46 and'47 formed in the rear rim 42 to slide, respectively, in the rear lateral slots 37 and 38 of the housing 25.

The rear rim 42 of the support 39 has a recess 48 formed therein (see FIGURE in the region adjacent to the lower rear slot 36 formed in the housing 25. Also, the frusto-conical section 43 is provided with an opening 49 to receive the forked end portion 51 of an arm 52. The arm itself is shown in detail in FIGURE 4. It extends toward the rear of the structure where it is provided with an outwardly extending key 53. The key is provided with lateral flanges 54 and is adapted to slide in the lower rear slot 36 of the housing 25 with the flanges 54 thereof bearing on the inside of the housing. A screw 55 is threaded through the key 53 and is adjusted by means of the operation of the arm 52 so as to enable the adjustment of the elevation of the rear part of the half-shell yoke support 39. The elevating arm 52 also may be provided with a pair of spaced fins 56 which are adapted to move on opposite sides of a rib 57 of the yoke support 39 so as to laterally stabilize the elevating arm.

The deflection yoke 58, represented 'by the sectional views of one of the horizontal coils 59 and the ferrite core 61, is supported by and suitably attached to (by means not shown) the half-shell support 39 substantially as indicated in FIGURE 3.

A clamping screw 62 is threaded through the lower front key 44. Similarly, clamping screws 63 and 64 are threaded respectively into the rear lateral keys 46 and 47 of the yoke support 39. The purpose of these screws is to lock the yoke support 39 and the yoke 58 securely in the desired position relative to the electron guns and the beams produced thereby within the picture tube. With all of these screws loosened, the yoke support 39 and the yoke 58 carried thereby may be moved longitudinally of the axis of the picture tube with the various keys formed on the support sliding within the slots formed in the mounting 25. Cooperating with the clamping screws 62, 63 and 64 are generally U-shaped brackets 65, 66 and 67, respectively, which bear upon the outside surface of the housing 25 when the screws are tightened.

It is to be noted that the rear lateral keys 46 and 47 are somewhat narrower than the slots 37 and 38 in which they slide. The reason for this is to allow for vertical movement of these keys in their respective slots when the elevation of the rear end of the yoke support is adjusted by means of the operation of the arms 52 and the adjusting screw 55. Similarly, the lateral front keys 45 and 45a are slightly narrower than the slots 35 and 35a, in order to permit the required pivoting of the front end of the yoke support when the elevation of the rear portion is effected.

The problem encountered and the solution of it produced by the described yoke supporting mechanism is illustrated in FIGURES 6, 7 and 8. For the purpose of the following explanation, it is assumed that the adjusting screw 55 is withdrawn from the key 53 of the ele- 6 vating arm 52 of FIGURES 3, 4 and 5 to such an extent as to allow the rear rim 42 of the yoke support 39 to rest upon the inside surface of the rear section 29 of the housing 25, thereby placing the rear end of the deflection yoke at the lowest point relative to the tube neck, and to the three beams.

In FIGURE 6, there is illustrated a typical non-registration of the sides of the green, blue and red rasters in the absence of dynamic convergence and without proper adjustment of the yoke supporting mechanism embodying the present invention. The vertical center lines 68 of the red, green and blue rasters R, G'and B, respectively, are shown converged on the axis of the tube. In FIGURE 6 the blue raster is represented by three vertical lines of which the line 68 is located substantially centrally of the face plate 13 of the picture tube and the lines 69 and 71 are located respectively in the left and right hand regions of the tube face. By virtue of the arrangement of the electon beams relative to the longitudinal axis 22 of the picture tube as illustrated in FIGURE 2, it is to be expected that the location of the blue gun 16 directly over the tube axis would produce a raster which is centrally located horizontally of the tube face. Such a condition is represented in FIGURE 6.

Also, by reason of the location of the red beam at the left of the tube axis 22 as viewed from the tube face 14 and as depicted in FIGURE 2, the red raster is shifted to the right relative to the blue raster. As indicated in FIGURE 6, when the green, blue and red vertical lines 68 are converged at the center of the tube, the red raster lines 73 and 74, respectively, in the left and right hand areas are located to the right of the associated blue raster lines 69 and 71. For similar reasons, when the central lines 68 of all three rasters are converged at the center of the screen, the left and right green lines 76 and 77, respectively, are located to the left of the associated blue raster lines 69 and 71.

FIGURE 7 depicts the resulting rasters scanned by the the three beams when static and dynamic convergence is applied but without proper adjustment of the yoke supporting structure. All three central lines 68 of the blue, red and green rasters coincide substantially at the middle of the screen of the face plate 13. At the left side of the picture area the red and green lines 73 and 76 coincide with one another but not with the blue line 69 which lies to the left of the two converged lines. Similarly, the right hand red and green lines 74 and 77 coincide with one another but not with the associated blue line 71 which lies to the right of the converged lines. The width W of the blue raster is somewhat greater than the width W of the converged red and green rasters.

The condition represented in FIGURE 7 is rectified by application of the present invention. As originally assumed, the rear end of the deflection yoke is at its lowest elevation relative to the tube neck and to the three beams. In order to correct the mis-registration of rasters illustrated in FIGURE 7, the elevating screw 55 is adjusted to raise the rear end of the deflection yoke relative to the tube neck. When this is done to the proper degree, coincidence is achieved of all three red, green and blue rasters .as depicted in FIGURE 8. All vertical lines of the three rasters coincide substantially with one another to produce a width W of the composite raster. It is to be noted that the width W is somewhat smaller than the width W of the blue raster and is somewhat larger than the width W of the combined red and green rasters as illustrated in FIGURE 7. In other words, the elevation of the rear end of the deflection yoke has caused the sides of the blue raster to move toward the center and the sides of the red and green rasters to move away from the center.

If, after having converged the red and green rasters with one another by means of the static and dynamic magnetic convergence apparatus, it is found that the blue raster is smaller in width than the combined red and green rasters,

complete registrations of all these rasters can be affected by lowering the rear end of the deflection yoke relative to the three beams. In such case, the sides of the blue raster are caused to move away from the center and the sides of the red and green rasters are made to move toward the center.

What is claimed is:

1. An adjustable mounting for a deflection yoke for a multiple electron beam color picture tube having a flared front section housing a luminescent screen and a small cylindrical rear neck section housing a plurality of electron guns and comprising:

a hollow generally cylindrical housing having a front end adapted to be pressed into engagement with the rear portion of said flared front section of said tube and a rear end provided with means adapted to be clamped to said neck section of said tube;

a half-shell upwardly-opening yoke suport having front and rear approximately semi-circular rims and means including a connecting section joining said rims;

a plurality of spaced slots formed in said housing adjacent said front end;

one lower and a plurality of lateral slots formed in said housing adjacent said rear end;

a plurality-of spaced outwardly-extending keys formed in the front rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the plurality of spaced slots formed in the front end of said housing;

a plurality of spaced outwardly-extending keys formed in the rear rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lateral slots formed in the rear end of said housing;

an arm extending longtiudinally of said picture tube and pivotally supported at its front end in the connecting section of said half-shell yoke support;

an outwardly-extending key formed in the rear end of said arm and adapted for movement longitudinally of said tube in the lower rear slot formed in said housing; and

means engaging the key formed in said arm with the rear rim of said half-shell yoke support and operable to change the elevation ofthe rear end of said yoke support relative to the neck section of said picture tube.

2. An adjustable mounting for a deflection yoke for a multiple electron beam color picture tube having a flared front section housing a luminescent screen and a small cylindrical rear neck section housing a plurality of electron guns and comprising:

a hollow generally cylindrical housing having a front end adapted to be pressed into engagement with the rear portion of said flared front section of said tube and a rear end provided with rnean adapted to be clamped to said neck section of said tube;

a half-shell upwardly opening yoke support having front and rear approximately semi-circular rims and means including a connecting section joining said rims;

one lower and a plurality of lateral inwardly-opening slots formed in said housing adjacent both of said front and rear ends;

one lower and a plurality of lateral outwardly-extending keys formed in the front trim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lower and lateral slots formed in the front end of said housing;

a plurality of lateral outwardly-extending keys formed in the rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lateral slots formed in the rear end of said housing; 7

an arm extending longitudinally of said picture tube and pivotally supported at its front end in the connecting section of said half-shell yoke support;

an outwardly-extending key with lateral flanges formed in the rear end of said arm and adapted for movernent longitudinally of said tube in the lower rear slot formed in said housing with said flanges being in sliding engagement with the inner surface of said housing; and

an adjusting screw extending through a threaded hole in said flanged key and into engagement with the rear rim of said half-shell yoke support and operable to change the elevation of the rear end of said yoke support relative to the neck section of said picture tube.

3. An adjustable mounting for a generally fustoconical deflection yoke for a multiple electron beam color picture tube having a flared from section housing a luminescent screen and a small cylindrical rear neck section housing a plurality of electron guns and comprising:

a hollow generally cylindrical housing having a front end adapted to be pressed int-o engagement with the rear portion of said flared front section of said tube and a rear end provided with means adapted to be clamped to said neck section of said tube;

a half-shell upwardly-opening yoke support having front and rear approximately semicircular rims and means including a generally frusto-conical section joining said rims;

one lower and two lateral inwardly-opening slots formed in said housing adjacent both of said front and rear ends;

one lower and two lateral outwardly-extending keys formed in the front rim of said half-shell yoke supsport and adapted for movement longitudinally of said picture tube respectively in the lower and lateral slots formed in the front end of said housing;

two lateral outwardly-extending key-s formed in the rear rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lateral slots formed in the rear end of said housing;

an arm extending longitudinally of said picture tube and pivotally supported at its front end in the frustoconical section of said half-shell yoke support;

an outwardly-extending key with lateral flanges formed in the rear end of said arm and adapted for movement longitudinally of said tube in the lower rear slot formed in said housing with said flanges-being in sliding engagement with the inner surface of said housing; and

an adjusting screw extending through a threaded hole in said flanged key and into engagement with the the rear rim of said half-shell yoke support and operable to change the elevation of the rear end of said yoke support relative to the neck section of said picture tube.

4. An adjustable mounting for a generally frustoconical deflection yoke for a multiple electron beam color picture tube having a flared front section housing a luminescent screen and a small cylindrical rear neck section housing a plurality of electron guns and comprising:

A hollow generally cylindrical housing having a front end adapted to be pressed into engagement with the rear portion of said flared front section of said tube and a rear end provided with means adapted to be clamped to said neck section of said tube;

a half-shell upwardly-opening yoke support having front and rear approximately semi-circular rims respectively of relatively large and small radii of curvature and means including a generally frusto-conical section joining said rims;

one lower and two later-a1 inwardly-opening slots formed in said housing adjacent both of said front and rear ends;

one lower and two lateral outwardly-extending keys formed in the front rim of said half-shell yoke sup- .port and adapted for movement longitudinally of said picture tube respectively in the lower and lateral slots formed in the front end of said housing;

two lateral outwardly-extending keys formed in the rear rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lateral slots formed in the rear end of said housing;

an arm extending longitudinally of said picture tube and pivotally supported at its front end in the frustoconical section of said half-shell yoke support;

an outwardly-extending key with lateral flanges formed in the rear end of said arm and adapted for movement longitudinally of said tube in the lower rear slot fonmed in said housing with said flanges being in sliding engagement with the inner surface of said housing; and

an adjusting screw extending through a threaded hole in said flanged key and into engagement with the rear rim of said half-shell yoke support and operable to change the elevation of the rear end of said yoke support relative to the neck section of said picture tube.

5. An adjustable mounting for a generally frusto-conical deflection yoke for a multiple electron beam color picture tube having a flared front section housing a luminescent screen and a small cylindrical rear neck section housing a plurality of electron guns and comprising:

a hollow generally cylindrical housing having a front end adapted to be pressed into engagement with the rear portion of said flared frontsection of said tube and a rear end provided with means adapted to be clamped to said neck section of said tube;

a half-shell upwardly-opening yoke support having front and rear approximately semi-circular rims respectively of relatively large and small radii of curvature and means including a generally frusto-conical section joining said rims;

one lower and two lateral inwardly-opening slots formed in said housing adjacent both of said front and rear ends;

one lower and two lateral outwardly-extending keys formed in the front rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lower and lateral slots formed in the front end of said housing;

two lateral outwardly-extending keys formed in the rear rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lateral slots formed in the rear end of said housing;

an arm extending longitudinally of said picture tube and pivotally supported at its front end in the frustoconical section of said half-shell yoke support;

an outwardly-extending key with lateral flanges formed in the rear end of said arm and adapted for movement longitudinally of said tube in the lower rear slot formed in said housing with said flanges being in sliding engagement with the inner surface of said housing;

an adjusting screw extending through a threaded hole in said flanged key and into engagement with the rear rim of said half-shell yoke support and operable to change the elevation of the rear end of said yoke support relative to the neck section of said picture tube; and

means including a pair of clamping screws extending into respective threaded holes in said two lateral rear rim keys of said half-shell yoke support to fix said support in said housing after said longitudinal and elevational adjustments of said support relative to said housing have been made.

6. An adjustable mounting for a generally frusto-conical deflection yoke for a multiple electron beam color picture tube having a flared front section housing a luminescent screen and a small cylindrical rear neck section housing a plurality of electron guns and comprising:

a hollow generally cylindrical housing having a front end adapted to be pressed into engagement with the rear portion of said flared front section of said tube and a rear end provided with means adapted to be clamped to said neck section of said tube;

a half-shell upwardly-opening yoke support having front and rear approximately semicircular rims respectively of relatively large and small radii ofcurvature and means including a generally frusto-conical section joining said rims;

one lower and two lateral inwardly-opening slots formed in said housing adjacent both of said front and rear ends;

one lower and two lateral outwardly-extending keys formed in the front rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lower and lateral slots formed in the front end of said housing;

two lateral outwardly-extending keys formed in the rear rim of said half-shell yoke support and adapted for movement longitudinally of said picture tube respectively in the lateral slots formed in the rear end of said housing;

an arm extending longitudinally of said picture tube and pivotally supported at its front end in the frustoconical section of said half-shell yoke support;

an outwardly-extending key with lateral flanges formed in the rear end of said arm and adapted for movement longitudinally of said tube in the lower rear slot formed in said housing with said flanges being in sliding engagement with the inner surface of said housing;

an adjusting screw extending through a threaded hole in said flanged key and into engagement with the rear rim of said half-shell yoke support and operable to change the elevation of the rear end of said yoke support relative to the neck section of said picture tube;and

a pair of clamping screws extending into respective threaded holes in said two lateral rear rim keys of said half-shell yoke support and a single clamping screw extending into a threaded hole in said lower front rim key of said half-shell yoke support to fix said support in said housing after said longitudinal and elevational adjustments of said support relative to said housing have been made.

7. In color television display apparatus employing a tri-color cathode ray tube having a luminescent screen comprising phosphors capable of producing red, green and blue light when excited by electron beams and having respective sources of three'electron beams which traverse pre-deflection paths that are spaced symmetrically about the longitudinal axis of said tube with said blue lightproducing beam being horizontally above and vertically in the same plane with said axis, and said red and green light-producing beams being horizontally equally below and vertically equally on opposite sides of said axis, the combination comprising:

means including a deflection yoke mounted externally of said tube in a region between said electron beam sources and said screen and energizable to deflect said beams to scan respective red, green and blue rasters at said screen, and vertical lines of said red and green rasters being converged with one another throughout and with vertical lines of said blue raster in central portions but being subject to misconvergenoe with vertical lines of said blue raster in left and right side portions; and,

means for changing the elevation of the end of said yoke adjacent said electron beam sources relative to the paths of said electron beams to effect convergence of all vertical lines of said red, green and blue rasters.

8. In color television display apparatus employing a tri-color cathode ray tube having -a luminescent screen comprising phosphors capable of producing red, green and blue light when excited by electron beams and having respective sources of three electron beams which traverse pre-deflection paths that are spaced symmetrically about the longitudinal axis of said tube with said blue lightproducing beam being horizontally above and vertically in the same plane with said axis, and said red and green light-producing beams being horizontally equally below and vertically equally on opposite sides of said axis, the combination comprising:

means including a deflection yoke mounted externally of said tube with its rear end facing said electron beam sources and its front end facing said screen and energizable to deflect said beams to scan respective red, green and blue rasters at said screen, vertical lines of said red, green and blue rasters being converged in central portions but said blue raster tending to be of a size different from said red and green rasters in left and right side portions; and,

means for changing in one vertical sense the elevation of the rear end of said yoke relative to the paths of said electron beams to decrease the size of said blue raster and to increase the size of said red and green rasters and for changing in the opposite vertical sense the elevation of the rear end of said yoke relative to the paths of said electron beams to increase the size of said blue raster and to decrease the size of said red and green rasters.

9. In color television display apparatus employing a tricolor cathode ray tube having a luminescent screen comprising phosphors capable of producing red, green and blue light when excited by electron beams and having respective sources of three electron beams which traverse pre-deflection paths that are spaced symmetrically about the longitudinal axis of said tube with said blue light-producing beam being horizontally above and vertically in the same plane with said axis, and said red and green lightproducing beams being horizontally equally below and vertically equally on opposite sides of said axis, the combination comprising:

means including a deflection yoke mounted externaly of said tube in a region betwen said electron beam sources and said screen and energizable to deflect said beams to scan respective red, green and blue rasters at said screen, and vertical lines of said red and green rasters being converged with one another throughout and with vertical lines of said blue raster in central portions but being subject to misconvergence with vertical lines of said blue raster in 'left and right side portions; and

means for raising the end of said yoke adjacent said electron beam sources relative to the paths of said electron beams to decrease the horizontal displacement from the center of vertical lines of said blue raster and to increase the horizontal displacement from the center of vertical lines of said red and green rasters, whereby to effect convergence of all vertical lines of said red, green and blue rasters.

References Cited by the Examiner UNITED STATES PATENTS 2,501,516 3/1950 Holden 313--76 2,880,367 3/1959 Caprio 31377 3,201,629 8/1965 Ammerman 3 l371 JAMES W. LAWRENCE, Primary Examiner.

V. LA FRANCHI, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,302, 050 January 31, 1967 Maximilian J. Obert et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 6, for "tudinnal" read tudinal line 66, for "arangement" read arrangement column 5, line 32, strike out "adjusted by means of the operation of the arm '52" and insert instead adapted to impinge upon the inside of the recess 48 line 64, for "arms" read arm column 7, line 30, for "spaced read lateral line 55, for "mean" read means line 69, before "rim" insert rear column 8, line 13, for "fustoconical" 1 read frusto-conical Signed and sealed this 28th day of November 1967.

(SEAL) Attest:

EDWARD M.FLETCHE-R,JR. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

7. IN COLOR TELEVISION DISPLAY APPARATUS EMPLOYING A TRI-COLOR CATHODE RAY TUBE HAVING A LUMINESCENT SCREEN COMPRISING PHOSPHORS CAPABLE OF PRODUCING RED, GREEN AND BLUE LIGHT WHEN EXCITED BY ELECTRON BEAMS AND HAVING RESPECTIVE SOURCES OF THREE ELECTRON BEAMS WHICH TRAVERSE PRE-DEFLECTION PATHS THAT ARE SPACED SYMMETRICALLY ABOUT THE LONGITUDINAL AXIS OF SAID TUBE WITH SAID BLUE LIGHTPRODUCING BEAM BEING HORIZONTALLY ABOVE AND VERTICALLY IN THE SAME PLANE WITH SAID AXIS, AND SAID RED AND GREEN LIGHT-PRODUCING BEAMS BEING HORIZONTALLY EQUALLY BELOW AND VERTICALLY EQUALLY ON OPPOSITE SIDES OF SAID AXIS, THE COMBINATION COMPRISING: MEANS INCLUDING A DEFLECTION YOKE MOUNTED EXTERNALLY OF SAID TUBE IN A REGION BETWEEN SAID ELECTRON BEAM SOURCES AND SAID SCREEN AND ENERGIZABLE TO DEFLECT SAID BEAMS TO SCAN RESPECTIVE RED, GREEN AND BLUE RASTERS AT SAID SCREEN, AND VERTICAL LINES OF SAID RED AND GREEN RASTERS BEING CONVERGED WITH ONE ANOTHER THROUGHOUT AND WITH VERTICAL LINES OF SAID BLUE RASTER IN CENTRAL PORTIONS BUT BEING SUBJECT TO MISCONVERGENCE WITH VERTICAL LINES OF SAID BLUE RASTER IN LEFT AND RIGHT SIDE PORTIONS; AND MEANS FOR CHANGING THE ELEVATION OF THE END OF SAID YOKE ADJACENT SAID ELECTRON BEAM SOURCES RELATIVE TO THE PATHS OF SAID ELECTRON BEAMS TO EFFECT CONVERGENCE OF ALL VERTICAL LINES OF SAID RED, GREEN AND BLUE RASTERS. 